Record-breaking railgun shoots bullet 1.6km in one second

There wasn't much left of the 23-pound (10kg) bullet, just a
scalded piece of squat metal. That's what happens when an enormous
electromagnetic gun sends its ammo rocketing 5,500 (1.6km) feet in
a single second.

The gun that fired the bullet is the US Navy's experimental railgun. The gun has no
moving parts or propellants -- just a king-sized burst of energy
that sends a projectile flying. And today its parents at the Office
of Naval Research sent 33 megajoules through it, setting a new
world record and making it the most powerful railgun ever
developed.

Reporters were invited to watch the test at the Dalghren Naval
Surface Warfare Center. A tangle of two-inch thick coaxial cables
hooked up to stacks of refrigerator-sized capacitors took five minutes to power juice
into a gun the size of a schoolbus built in a warehouse. With a
1.5-million-ampere spark of light and a boom audible in a room 50
feet (15m) away, the bullet left the gun at a speed of Mach 8.

All that energy was "dump[ed] in 10 milliseconds," says Charles
Garrett, project manager at Dahlgren for the railgun.

But since there no explosion powering the projectile, why should
the railgun have made any noise at all? Answer: the bullet went so
fast it released a sonic boom.

Since 2005, the Navy has spent $211 million (£133m) testing
whether it can harness electromagnetic energy into a gun. The
ultimate goal is to fire the gun at 64 megajoules, making it
capable of sending a bullet 200 miles (321km) in six minutes.
That's 10 times farther than the US Navy's already-powerful guns
can fire, keeping its ships far out of range of enemy anti-ship
systems.

The Navy wants to put the railgun on a ship and power it through the ship's batteries, something
that'll take years to develop. Since the gun's power can be
adjusted -- it depends only on the batteries and the capacitors on
board a ship, railgun scientists explained -- it could
theoretically be used to stop cruise missiles or even ballistic
missiles.

That's still a long way off. The Office of Science and
Technology will keep running tests until 2017, largely for "thermal
management," says program manager Roger Ellis, basically to ensure
that the materials used for the gun don't get as fried as the
bullet under the intense power generated. The Navy guesstimates
that it'll be ready for shipboard defense between 2020 and
2025.